Maghemite(γ-Fe_2O_3) nanoparticles enhance dissimilatory ferrihydrite reduction by Geobacter sulfurreducens: Impacts on iron mineralogical change and bacterial interactions

Microbially mediated bioreduction of iron oxyhydroxide plays an important role in the biogeochemical cycle of iron.Geobacter sulfurreducens is a representative dissimilatory ironreducing bacterium that assembles electrically conductive pili and cytochromes.The impact of supplementation withγ-Fe_2O_3 nanoparticles(NPs)(0.2 and 0.6 g)on the G.sulfurreducens-mediated reduction of ferrihydrite was investigated.In the overall performance of microbial ferrihydrite reduction mediated byγ-Fe_2O_3 NPs,stronger reduction was observed in the presence of direct contact withγ-Fe_2O_3 NPs than with indirect contact.Compared to the production of Fe(Ⅱ)derived from biotic modification with ferrihydrite alone,increases greater than 1.6-and 1.4-fold in the production of Fe(Ⅱ)were detected in the biotic modifications in which direct contact with 0.2 g and 0.6 gγ-Fe_2O_3 NPs,respectively,occurred.X-ray diffraction analysis indicated that magnetite was a unique representative iron mineral in ferrihydrite when active G.sulfurreducens cells were in direct contact withγ-Fe_2O_3 NPs.Because of the sorption of biogenic Fe(Ⅱ)ontoγ-Fe_2O_3 NPs instead of ferrihydrite,the addition ofγ-Fe_2O_3 NPs could also contribute to increased duration of ferrihydrite reduction by preventing ferrihydrite surface passivation.Additionally,electron microscopy analysis confirmed that the direct addition ofγ-Fe_2O_3 NPs stimulated the electrically conductive pili and cytochromes to stretch,facilitating long-range electron transfer between the cells and ferrihydrite.The obtained findings provide a more comprehensive understanding of the effects of iron oxide NPs on soil biogeochemistry.

Analysis of semen quality of 38 905 infertile male patients during 2008- 2016 in Wenzhou, China

This study analyzed the trend in semen quality of infertile male patients in Wenzhou,China,based on the data obtained from 38905 patients during 2008-2016 in The First Affiliated Hospital of Wenzhou Medical University(Wenzhou,China).The results showed that only 24.9%of the patients had normal semen quality.For the semen quality of infertile male patients,that of the workers and 40-year-olds was significantly worse than the other occupational and age groups.For all the infertile patients,low semen volume,asthenozoospermia,and teratozoospermia accounted for 8.4%,50.5%,and 54.1%,respectively.During 2008-2016,the annual mean percentage of fast forward motile spermatozoa,percentage of total forward motile spermatozoa,and percentage of spermatozoa with normal morphology decreased linearly with slopes of-2.11,-2.59,and-0.70,respectively.The proportion of patients with asthenozoospermia and multi-abnormal spermatozoa increased during 2008-2016 with slopes of 4.70 and 4.87,respectively,while for low semen volume,it decreased with a slope of-0.47 in the same time period.The proportion of patients with teratozoospermia increased from 2008 to 2011 and from 2011 to 2016 with slopes of 17.10 and 2.09,respectively.In general,the deteriorating trend of semen quality of infertile male patients in Wenzhou was obvious.Future efforts should be made to reveal the adverse influences on semen quality,such as occupational exposure,environmental quality,and living habits.Furthermore,more pervasive reproduction health education is necessary.

Enhanced the photoelectrochemical performance of Bi_(2)XO_6(X = W, Mo) for detecting hexavalent chromium by modification of CuS

In this work, Bi2XO6(X = W, Mo) are synthesized at different temperatures. The results of tests find the optimal temperatures of Bi_(2)WO_(6) and Bi_(2)MoO_(6) are 180 and 160 °C(BW-180, BM-160). Then, BW-180 and BM-160 are further compounded with different contents of CuS. The results of photoelectrochemical(PEC) tests show that CuS can improve the PEC performance of semiconductor materials, and it has better performance when CuS mass fraction is 5%. These maybe the photoelectron potentials generated by Cu S/Bi_(2)XO_(6)(X = Mo, W) heterojunction reduce the combination of photogenerated electrons and holes. When the PEC sensor based on 5%-CuS/BW-180 detects Cr(VI), it has a linear range of 1–80 μmol/L with detection limit of 0.95 μmol/L, while the PEC sensor based on 5%-CuS/BM-160 detects Cr(VI) has a linear range of 0.5–230 μmol/L and a detection limit of 0.12 μmol/L. Thus, 5%-CuS/Bi_(2)XO_(6) has potential application in hexavalent chromium detection.

Will male semen quality improve with environmental quality?

Wenzhou has improved its environmental quality because of comprehensive environmental remediation;nevertheless,the semen quality of infertile males remains unclear.This study determined whether better environmental quality improved semen quality in this region.We recorded semen quality data from 22962 infertile males from January 2014 to November 2019 at the Center for Reproductive Health of The First Affiliated Hospital of Wenzhou Medical University(Wenzhou,China).Patients were predominantly 30–35 years old(33.1%)and workers(82.0%),with high school education or lower(77.6%);more than a half of the patients(52.6%)were Wenzhou household registration;and most patients(77.5%)had abnormal semen quality.Patients who were older than 40 years and workers,and those with Wenzhou household registration,had significantly worse semen quality(all P<0.05).From 2014 to 2019,progressive sperm motility,total sperm motility,and semen volume showed increasing linear trends in all patients(P=0.021,0.030,and 0.005,respectively),yet normal sperm morphology showed a linearly decreasing trend(P=0.046).Sensitivity analyses for subgroups yielded similar results.In conclusion,the improvement of environmental quality and better function of the accessory glands are associated with progressive sperm motility,total sperm motility,and semen volume.Normal sperm morphology is influenced by occupational exposures and personal lifestyle and does not improve with environmental quality.